Fusible Link Unit and Electric Junction Box

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2024-144355 filed on Aug. 26, 2024, the contents of which are incorporated herein by reference.

The present disclosure relates to a fusible link unit and an electric junction box using the fusible link unit.

In the related art, a fusible link unit has been proposed, in which a bus bar having a fusing portion that fuses at a predetermined current value is embedded in a resin housing (for example, see Patent Literature 1).

Patent Literature 1: JP2021-166160A

Incidentally, in a situation where a charge amount of a battery mounted on a vehicle such as an automobile is extremely reduced, electric power may be supplied to the battery from the outside of the vehicle (for example, another relief vehicle). A relief terminal for connecting a relief tool (for example, a clip of a booster cable) used for power supply from the outside may be provided in an electric junction box of a vehicle. However, when a dedicated bus bar or the like used as a relief terminal is provided in the electric junction box, such a bus bar may hinder miniaturization of the electric junction box. It may be difficult to provide such a dedicated bus bar or the like at a desired position depending on a size of a surplus space of the electric junction box.

An object of the present disclosure is to provide a fusible link unit and an electric junction box capable of reducing a size of the electric junction box while providing a relief terminal in the electric junction box.

In order to achieve the above-described object, a fusible link unit and an electric junction box according to the present disclosure are characterized as follows.

A fusible link unit of the present disclosure includes a conductor having a fuse function, and a housing that accommodates the conductor. The conductor includes an input terminal that inputs electric power from a power source, an output terminal that outputs the electric power, a fusing portion disposed on an energization path from the input terminal to the output terminal, and a relief terminal portion capable of connecting a relief tool for supplying the electric power to the power source from outside. The input terminal and the relief terminal portion are provided on a continuous exposed piece of the conductor exposed from the housing.

An electric junction box of the present disclosure includes the fusible link unit described above and a case having an accommodation space in which the fusible link unit is accommodated.

According to the fusible link unit and the electric junction box of the present disclosure, a part of a conductor (for example, a bus bar) having a fuse function is used as a relief terminal portion to which a relief tool can be connected. In other words, the fusible link unit has a function as a relief terminal in addition to its original overcurrent interruption function. Therefore, it is not necessary to provide a dedicated bus bar or the like used as the relief terminal portion in the electric junction box. Therefore, in the fusible link unit and the electric junction box of the present disclosure, it is possible to reduce the size of the electric junction box while providing the relief terminal in the electric junction box.

Furthermore, as another effect, in the fusible link unit and the electric junction box of the present disclosure, the relief terminal portion and the input terminal are commonly provided on a continuous exposed piece of the conductor exposed from the housing. In general, an input terminal that inputs electric power from a power source such as an in-vehicle battery to the fusible link unit is disposed at a peripheral edge of the electric junction box in terms of the operability of work of connecting a power cable. Therefore, when the fusible link unit is attached to the electric junction box, the relief terminal portion is also disposed on the peripheral edge of the electric junction box. Therefore, as compared with a case where the relief terminal portion is disposed at the center of the electric junction box or the like, the operability of a user when a relief operation is actually performed can be improved.

The present disclosure has been briefly described above. Further, details of the present disclosure will be clarified by reading modes for carrying out the invention described below with reference to the accompanying drawings.

1 1 44 42 47 1 FIG. 1 FIG. Hereinafter, a fusible link unitaccording to an embodiment of the present disclosure will be described with reference to the drawings. The fusible link unithas a function of electrically connecting a battery (not shown) connected to an input terminal(seeand the like), external loads (not shown) connected to output terminals(see), and a DC/DC converter (not shown) connected to another input terminal, and disconnecting the battery from the external loads and the DC/DC converter when a current having a magnitude exceeding a rated current flows.

1 FIG. 1 Hereinafter, for convenience of description, a “front-rear direction”, a “left-right direction”, and an “upper-lower direction”, “front”, “rear”, “left”, “right”, “upper”, “lower” are defined as shown in. The “front-rear direction”, the “left-right direction”, and the “upper-lower direction” are orthogonal to one another. These directions are merely defined for the convenience of description, and do not necessarily correspond to, for example, the front-rear direction, the left-right direction, and the upper-lower direction of the automobile or the like when the fusible link unitis mounted on the automobile or the like.

1 3 FIGS.to 2 FIG. 1 10 20 30 20 20 30 1 As shown in, the fusible link unitincludes a fuse element, a housing, and a coverattached to the housing. As can be understood from, each of the housingand the coverhas a shape that is plane-symmetrical with respect to a plane (a symmetry plane) passing through the center in the front-rear direction and perpendicular to the front-rear direction. Hereinafter, the members constituting the fusible link unitwill be described in order.

20 20 10 10 20 21 22 21 1 3 FIGS.to 3 FIG. First, the housingwill be described. The housingis a resin molded body formed of a resin material integrally with the fuse element(insert molding) to cover (embed) most of the fuse element. As can be understood from(particularly,), the housinggenerally includes a substantially rectangular parallelepiped housing bodyextending in the left-right direction and the upper-lower direction, and a substantially rectangular parallelepiped housing protruding portionprotruding rightward from an upper right corner of the housing body.

23 31 30 21 21 Substantially rectangular cover accommodating recessfor accommodating a pair of side wall portions(to be described later) of the coverare respectively formed in front and rear end surfaces of the housing bodyso as to be recessed in a thickness direction (the front-rear direction) of the housing body.

23 21 24 24 24 24 23 24 24 24 24 24 a b a b a b a b In each of the substantially rectangular bottom surfaces of the pair of front and rear cover accommodating recessesof the housing body, a plurality of (four in this example) openingsare defined and formed to be aligned in the left-right direction in a lower region thereof, and a single openingis formed at an upper right end thereof. Each of the openingsand the openingis a rectangular hole penetrating in the front-rear direction to communicate the bottom surfaces of the pair of front and rear cover accommodating recesseswith each other. Hereinafter, when it is not necessary to distinguish the openingand the opening, each of the openingand the openingmay be referred to as an “opening”.

23 21 25 30 20 33 30 25 1 FIG. Each of the substantially rectangular bottom surfaces of the pair of front and rear cover accommodating recessesof the housing bodyis formed with a locking projectionat a central portion in the left-right direction of an upper end thereof. In a state where the coveris attached to the housing, a pair of front and rear locking holes(to be described later) of the coverare engaged with the pair of front and rear locking projections(see).

10 10 40 50 43 43 40 3 FIG. a b Next, the fuse elementwill be described. As shown in, the fuse elementincludes a bus bar(a flat plate-shaped metal member), and a plurality of (in this example, five) low-melting bodiesdisposed in a plurality of (in this example, four) fusing portionsand a single fusing portion, which are parts of the bus bar.

4 FIG. 3 FIG. 40 40 40 20 21 22 20 As shown in, the bus barhas a flat plate shape extending in the left-right direction and the upper-lower direction, and a plate thickness (a length in the front-rear direction) of the bus baris constant over the entire region in this example. Most of the bus baris embedded in the housing(the housing body+ the housing protruding portion) to extend along the symmetry plane including the symmetry plane of the housing(see).

3 FIG. 40 41 42 47 43 43 20 21 22 43 43 43 43 43 a b a b a b As shown in, the bus barincludes a connection portion, the plurality of (four in this example) output terminals, the input terminal, the plurality of (four in this example) fusing portions, and the single fusing portionas portions exposed to an outside from the housing(the housing body+the housing protruding portion). Hereinafter, when it is not necessary to distinguish the fusing portionand the fusing portion, each of the fusing portionand the fusing portionmay be referred to as a “fusing portion”.

41 21 20 41 44 41 20 45 45 20 44 53 45 46 45 46 45 53 45 45 54 53 44 45 41 40 20 7 FIG. 7 FIG. The connection portionis a substantially rectangular flat plate-shaped portion protruding leftward from a left end surface of the housing bodyof the housingand extending in the upper-lower direction. A lower region of the connection portionfunctions as the input terminal, and an upper region of the connection portion(in particular, a portion protruding upward from an upper end of the housing) functions as the relief terminal portion. The relief terminal portionhas a shape separated upward from the housing. A battery terminal (not shown) connected to a battery post of a vehicle battery is connected to the input terminal. A clip(see) of a booster cable is connected to the relief terminal portion. A curved portionthat is curved and extends in the left-right direction such that an upper end edge of the relief terminal portionextending in the left-right direction rises in a plate thickness direction (more specifically, a front side). By providing the curved portionin the relief terminal portion, as shown in, the work when the clipis connected to the relief terminal portionby clamping the upper end edge of the relief terminal portionwith a pair of clamping portionsof the clipof the booster cable is facilitated. As described above, the input terminaland the relief terminal portionare commonly provided in the connection portionhaving a continuous plate shape, which is a part of the bus barexposed from the housing.

42 21 20 24 42 a The plurality of (four) output terminalsprotrude downward from the lower end surface of the housing bodyof the housing, and are arranged side by side in the left-right direction corresponding to the plurality of openings. A terminal (not shown) provided at an end of an electric wire extending from a corresponding external load is connected to each output terminal.

47 22 20 24 47 b The input terminalprotrudes downward from a lower end surface of the housing protruding portionof the housing, and is disposed corresponding to the single opening. A terminal (not shown) provided at an end of an electric wire extending from the DC/DC converter is connected to the input terminal.

43 24 43 24 43 24 43 24 50 43 50 40 43 a a a a b b b b The plurality of (four) fusing portionsare located inside the corresponding openings. The fusing portionsare exposed to both the front side and the rear side through front and rear openings of the corresponding openings, and are visible from both the front side and the rear side. Similarly, the single fusing portionis located inside the single opening. The fusing portionis exposed to both the front side and the rear side through the front and rear openings of the opening, and is visible from both the front side and the rear side. The low-melting bodyis placed on one of front and rear surfaces (in this example, the front surface) of each fusing portion. A melting point of a material (for example, an alloy containing tin (Sn) as a main component) constituting the low-melting bodyis lower than a melting point of a material (for example, an alloy containing copper (Cu) as a main component) constituting the bus bar(the fusing portion).

4 FIG. 40 41 44 45 42 43 43 43 43 47 42 43 43 43 43 a b a b a b a b. As shown in, in the bus bar, the connection portion(the input terminal+the relief terminal portion) is connected to each of the plurality of output terminalsvia one or both of the fusing portionsand the fusing portion. In other words, the battery and the various kinds of external loads are electrically connected via one or both of the fusing portionsand the fusing portion. Similarly, the input terminalis connected to each of the plurality of output terminalsvia one or both of the fusing portionsand the fusing portion. In other words, the DC/DC converter and various kinds of external loads are electrically connected via one or both of the fusing portionsand the fusing portion

40 43 43 42 43 41 44 45 The bus baris designed such that the fusing portionis fused using Joule heat when a current having a magnitude exceeding the rated current flows. When the fusing portionis fused, the electrical connection between the output terminalconnected to the fused fusing portionand the connection portion(the input terminal+ the relief terminal portion) is disconnected.

43 43 43 50 43 50 43 50 43 43 50 43 43 43 43 43 50 50 43 10 50 The fusing principle of each fusing portionis as follows. When a current having a magnitude exceeding the rated current flows through the fusing portion, a temperature of the fusing portionreaches the melting point of the low-melting bodydue to heat (Joule heat) generated in the fusing portion, so that the low-melting bodymelts earlier than the fusing portion. When the melted (liquid-phase) low-melting bodycomes into contact with the fusing portion, the metal material constituting the fusing portiondiffuses into the low-melting bodyeven if the fusing portionitself has not yet reached the melting point. The fusing portionis gradually eroded by this diffusion, and the fusing portionis cut (fused). Based on the above-described fusing principle, the fusing portioncan be fused when the temperature of the fusing portionat a location where the low-melting bodyis placed reaches the melting point of the low-melting body(even if the temperature does not reach a melting point of the fusing portion). Accordingly, the fuse elementis blown at a more practical temperature (a melting point of the low-melting body).

30 30 30 43 43 10 1 20 1 FIG. Next, the coverwill be described. The coveris a molded body formed of a transparent resin material. The coverhas a function of covering and protecting the periphery of the fusing portionso that the fusing portionof the fuse elementcan be visually recognized from an outside of the fusible link unitin a state of being attached to the housing(see).

3 FIG. 30 31 32 31 33 31 25 20 1 As shown in, the coverincludes a pair of substantially rectangular flat plate-shaped side wall portionsextending in the upper-lower direction and the left-right direction and facing each other in the front-rear direction, and a coupling portioncoupling upper ends of the pair of front and rear side wall portionsto each other, and has a substantially U-shape that opens downward when viewed from the left-right direction. The pair of front and rear locking holesare formed in central portions in the left-right direction of the upper ends of the pair of front and rear side wall portionsso as to correspond to the pair of front and rear locking projectionsof the housing. The members constituting the fusible link unithave been described above.

30 21 20 30 21 20 30 21 30 21 31 23 21 24 33 30 25 21 3 FIG. The coverhaving the above configuration is attached to the housing bodyof the housing. In order to attach the coverto the housing bodyof the housing, as shown in, the coveris disposed on an upper side of the housing body, and the coveris slid downward relative to the housing bodyso that the pair of front and rear side wall portionsare respectively accommodated in the pair of front and rear cover accommodating recessesof the housing bodyand cover the plurality of (five) openingsfrom both front and rear sides. This sliding is continued until the pair of locking holesof the coverare engaged with the pair of locking projectionsof the housing body.

33 25 30 21 20 30 20 24 20 31 43 30 43 43 1 33 25 30 20 30 1 FIG. When the pair of locking holesare engaged with the pair of locking projections, the attachment of the coverto the housing bodyof the housingis completed (see). In a state where the attachment of the coverto the housingis completed, the plurality of (five) openingsof the housingare covered by the pair of side wall portionsfrom both front and rear sides. Accordingly, the plurality of fuse portionsare covered and protected by the coverat positions away from the fuse portionssuch that the fuse portionscan be visually recognized from an outside of the fusible link unit. The engagement between the pair of locking holesand the pair of locking projectionsprevents the coverfrom moving upward relative to the housing(that is, prevents the coverfrom falling off).

5 6 FIGS.and 5 7 FIGS.and 1 30 20 51 52 2 3 51 51 1 20 42 20 41 20 52 2 44 41 20 52 45 46 41 52 2 53 45 As shown in, the fusible link unitin a state where the attachment of the coverto the housingis completed is inserted from above and accommodated in accommodation spaces,provided inside a substantially rectangular parallelepiped case, which is a housing of the electric junction box(for example, a fuse box). The accommodation spaceis a hole that penetrates in the upper-lower direction and extending in the left-right direction, and the accommodation spaceaccommodates a portion of the fusible link unit(specifically, the entire housingand the plurality of (five) output terminalsextending downward from the housing) excluding the connection portionprotruding leftward from the housing. The accommodation spaceis a recessed portion (recess) that is located at a left peripheral edge of the caseand opens upward and forward, and the input terminal, which is a part of the connection portionprotruding leftward from the housing, is accommodated in the accommodation space. The relief terminal portion(including the curved portion), which is a part of the connection portion, protrudes outside the accommodation space(above an upper end of the case) (see). Accordingly, it is easy to connect the clipof the booster cable to the relief terminal portion.

3 1 2 40 45 53 44 1 3 44 44 3 45 44 41 40 3 45 3 45 20 42 20 1 51 52 3 45 52 3 As described above, in the electric junction boxin which the fusible link unitis accommodated in the case, a part of the bus baris used as the relief terminal portionto which the clipof the booster cable can be connected. Therefore, it is not necessary to separately provide a dedicated bus bar or the like used as a relief terminal portion as in the related art. Further, the input terminalfor inputting electric power from the battery to the fusible link unitis disposed at a left peripheral edge of the electric junction box. Therefore, the operability of the connection work between the input terminaland the power cable extending from the battery is improved. Further, since the input terminalis disposed in the left peripheral edge of the electric junction box, the relief terminal portioncommonly provided with the input terminalin the plate-shaped connection portion, which is a part of the bus bar, is also disposed in the left peripheral edge of the electric junction box, and thus the operability of the user can be improved as compared with a case where the relief terminal portionis disposed in the center or the like of the electric junction box. Further, the relief terminal portionhas a shape separated from the housingin a direction (upward) opposite to a direction (downward) in which the output terminalprotrudes from the housing. Accordingly, when the fusible link unitis fitted into the accommodation spaces,of the electric junction box, the relief terminal portioncan easily protrude outside (an upper side) the accommodation spaceof the electric junction box.

1 40 45 53 1 3 45 44 41 40 20 44 1 3 1 3 45 3 45 3 1 3 As described above, according to the fusible link unitof the present embodiment, a part of the bus barhaving a fuse function is used as the relief terminal portionto which the relief tool (the clipof the booster cable) can be connected. Therefore, when the fusible link unitis attached to the electric junction box, it is not necessary to separately provide a dedicated bus bar or the like used as a relief terminal portion as in the related art. Further, the relief terminal portionand the input terminalare commonly provided on a continuous exposed piece (the connection portion) of the bus barexposed from the housing. The input terminalfor inputting electric power from a power source to the fusible link unitis disposed in the peripheral edge of the electric junction boxin terms of the operability of connection work with a power cable. Therefore, when the fusible link unitis attached to the electric junction box, the relief terminal portionis also disposed on the peripheral edge of the electric junction box, and thus the operability of the user can be improved as compared with a case where the relief terminal portionis located at the center or the like of the electric junction box. As described above, the fusible link unitaccording to the present embodiment can reduce a size of the electric junction box.

1 45 46 41 40 53 45 Further, according to the fusible link unitof the present embodiment, the relief terminal portionincludes the curved portionthat is curved such that a part of the peripheral edge of the exposed piece (the connection portion) of the bus barrises in the plate thickness direction. Accordingly, it is easy to connect a relief tool (the clipof the booster cable) to the relief terminal portion.

1 45 20 42 1 51 52 3 45 52 3 Further, according to the fusible link unitof the present embodiment, the relief terminal portionhas a shape separated from the housingin a direction (upward) opposite to a direction (downward) in which the output terminalprotrudes. Accordingly, when the fusible link unitis fitted into the accommodation spaces,of the electric junction box, the relief terminal portioncan protrude outside the accommodation spaceof the electric junction box. Therefore, the operability of the user can be improved.

3 45 40 52 2 Further, according to the electric junction boxof the present embodiment, the relief terminal portion, which is a part of the bus bar, is disposed to protrude outside the accommodation spaceof the case. Accordingly, the operability of the user can be improved.

The present disclosure is not limited to the embodiment described above, and various modifications can be adopted within the scope of the present disclosure. For example, the present disclosure is not limited to the embodiment described above, and modifications, improvements, and the like can be appropriately made. In addition, materials, shapes, dimensions, numbers, arrangement locations, and the like of the respective constituent elements in the above embodiment are optionally selected and are not limited as long as the present disclosure can be implemented.

41 40 45 48 41 46 48 45 53 45 48 45 44 42 8 FIG. For example, in the above embodiments, an upper region of the exposed piece (the connection portion) of the bus baris used as the relief terminal portion. Here, as shown in, one or a plurality of recesses(so-called serrations) may be provided in the upper region of the connection portion, that is, in the vicinity of the curved portion. By providing such a recess, the user can easily visually recognize the relief terminal portion, and the clipof the booster cable can be firmly fixed to the relief terminal portion. The recessalso has a function of visually indicating that the relief terminal portionis provided at a position different from a normal energization path from the input terminalto the output terminal.

1 3 1 [1] A fusible link unit () including: 40 a conductor () having a fuse function; and 20 40 40 44 an input terminal () that inputs electric power from a power source, 42 an output terminal () that outputs the electric power, 43 44 42 a fusing portion () disposed on an energization path from the input terminal () to the output terminal (), and 45 53 a relief terminal portion () capable of connecting a relief tool () for supplying the electric power to the power source from outside, and a housing () that accommodates the conductor (), in which the conductor () includes 44 45 41 40 20 the input terminal () and the relief terminal portion () are provided on a continuous exposed piece () of the conductor () exposed from the housing (). Here, the characteristics of the embodiments of the fusible link unitand the electric junction boxaccording to the present disclosure described above will be briefly summarized and listed in the following [1] to [5].

According to the fusible link unit having the configuration of the above [1], a part of the conductor (for example, a bus bar) having a fuse function is used as a relief terminal portion to which a relief tool can be connected. In other words, the fusible link unit has a function as a relief terminal in addition to its original overcurrent interruption function. Therefore, it is not necessary to provide a dedicated bus bar or the like used as a relief terminal portion in an electric junction box. Therefore, in the fusible link unit of the present disclosure, it is possible to reduce the size of the electric junction box while providing the relief terminal in the electric junction box.

Furthermore, as another effect, in the fusible link unit having the present configuration, the relief terminal portion and the input terminal are commonly provided on a continuous exposed piece of the conductor exposed from the housing. In general, an input terminal that inputs electric power from a power source such as an in-vehicle battery to the fusible link unit is disposed at a peripheral edge of the electric junction box in terms of the operability of work of connecting a power cable. Therefore, when the fusible link unit is attached to the electric junction box, the relief terminal portion is also disposed on the peripheral edge of the electric junction box. Therefore, as compared with a case where the relief terminal portion is disposed at the center of the electric junction box or the like, the operability of a user when a relief operation is actually performed can be improved.

1 41 40 the exposed piece () of the conductor () has a plate shape, and 45 46 41 the relief terminal portion () has a curved portion () that is curved such that a part of a peripheral edge of the exposed piece () rises in a plate thickness direction. [2] The fusible link unit () according to [1], in which

According to the fusible link unit having a configuration of the above [2], the relief terminal portion has the curved portion that is curved such that a part of the peripheral edge of the exposed piece of the conductor rises in the plate thickness direction. Accordingly, it is easy to connect a relief tool (for example, a clip of a booster cable) to the relief terminal portion.

1 42 20 the output terminal () has a shape protruding from the housing () in a predetermined direction, and 45 20 the relief terminal portion () has a shape separated from the housing () in a direction opposite to the predetermined direction. [3] The fusible link unit () according to [1], in which

According to the fusible link unit having the configuration of the above [3], the relief terminal portion has a shape separated from the housing in a direction opposite to a direction in which the output terminal protrudes. Accordingly, for example, when the fusible link unit is fitted into the accommodation space of the electric junction box, the relief terminal portion can protrude outside the accommodation space of the electric junction box. Therefore, the operability of the user when a relief operation is performed can be improved.

3 1 the fusible link unit () according to any one of [1] to [3]; and 2 51 52 1 a case () having an accommodation space (,) in which the fusible link unit () is accommodated. [4] An electric junction box () including:

According to the electric junction box having the configuration of the above [4], a part of the conductor (for example, a bus bar) having a fuse function of the fusible link unit is used as a relief terminal portion to which a relief tool can be connected. In other words, the fusible link unit has a function as a relief terminal in addition to its original overcurrent interruption function. Therefore, it is not necessary to provide a dedicated bus bar or the like used as the relief terminal portion in the electric junction box. Therefore, in the fusible link unit of the present disclosure, it is possible to reduce the size of the electric junction box while providing the relief terminal in the electric junction box.

Furthermore, as another effect, in the electric junction box having the present configuration, the relief terminal portion and the input terminal of the fusible link unit are commonly provided on a continuous exposed piece of the conductor exposed from the housing. In general, an input terminal that inputs electric power from a power source such as an in-vehicle battery to the fusible link unit is disposed at a peripheral edge of the electric junction box in terms of the operability of work of connecting a power cable. Therefore, when the fusible link unit is attached to the electric junction box, the relief terminal portion is also disposed on the peripheral edge of the electric junction box. Therefore, as compared with a case where the relief terminal portion is disposed at the center of the electric junction box or the like, the operability of the user when the relief operation is actually performed can be improved.

3 1 45 40 52 the fusible link unit () is disposed such that at least a part of the relief terminal portion () of the conductor () protrudes outside the accommodation space (). [5] The electric junction box () according to [4], in which

According to the electric junction box having a configuration of the above [5], the relief terminal portion of the conductor is disposed to protrude outside the accommodation space of the case. Accordingly, the operability of the user when the relief operation is performed can be improved.